Thank you for your October 20, 2011, letter to the Occupational Safety and Health Administration (OSHA) for an answer to your specific questions regarding the health and safety issues involved when motor carriers use selective catalytic reduction with urea (SCR-urea) to meet new emission standards of the U.S. Environmental Protection Agency. Some designs to implement the new SCR-urea systems involve a small tank on the truck to hold the urea-based additive, also known as diesel exhaust fluid (DEF), which require periodic re-filling, much like trucks' diesel fuel tanks are refilled.

Your letter expressed concerns that during the filling process of the DEF tanks, or when performing maintenance on the SCR-urea systems, workers may be exposed to urea and its by-products. You also stated concerns that manufacturers are not providing adequate safety and health information on their material safety data sheets (MSDSs) for the urea solutions. You further stated that most filling stations do not yet have pumping systems in place for dispensing the DEF into tanks. Without pumping stations, truck drivers are required to manually pour the fluid into tanks and increase their risk of developing work-related musculoskeletal disorders (MSDs). You asked what OSHA was planning on doing to ensure that the workers which you represent are properly protected while using these SCR-urea systems.

OSHA reviewed information on these SCR-urea systems and held discussions with affected parties concerning the health and safety issues. A breakdown product of the DEF solution is the formation of a small amount of ammonia gas in the headspace of the DEF storage tank mounted near a truck's engine. OSHA recently wrote a letter to answer questions about potential hazards from ammonia to Ms. Carolyne Hathaway on May 12, 2011. In this letter, OSHA stated that affected employers are required to train their truck drivers and maintenance workers about potential hazards, including recommendations provided on manufacturer's MSDSs. For your convenience, we have enclosed a copy of this letter. You may also be interested in a recent case study in the January 2011 issue of the Journal of Occupational and Environmental Hygiene1.

OSHA's Hazard Communication standard (HCS), 29 CFR 1910.1200, applies to the SCR-urea operations and the manufacture of DEF products, and other OSHA standards may apply, as well. The HCS requires all chemical manufacturers and importers to evaluate the hazards of the chemicals they produce or import, and prepare labels and MSDs to convey the hazard information to their downstream customers. The downstream users (employer) must utilize this information to ensure that workers are protected from any identified hazards. Other OSHA standards that may apply to SCR-urea operations or the manufacture of DEF products include, but are not limited to, 29 CFR Part 1910, Subpart I, Personal Protective Equipment, and 29 CFR 1910.1000, Air Contaminants.

Regarding the risk of truck drivers developing MSDs, OSHA provides general guidance on ergonomics in a safety and health topics page,www.osha/SLTC/ergonomics/index.html. Egro risk factors to consider when assessing the job of filling tanks with DEF fluid include, but are not limited to, the weight of the containers, excessive force or exertion, awkward postures, and repetitive motions. The DEF fluid may be distributed in various sizes of containers (1 gallon through 330 gallons), so designing the dispensing operation and adapting appropriate work practice controls should be done to address the associated hazards.

Employers seeking assistance in evaluating their workplaces can locate the nearest OSHA Consultation Office by visiting www.osha.gov or calling 1-800-321-OSHA (6742). Additionally, the National Institute for Occupational Safety and Health (NIOSH) performs health hazard evaluations at specific workplaces, and more information may be found at www.cdc.gov/niosh/hhe. Workers, worker representatives, or employers can request that NIOSH perform a health hazard evaluation at their place of work.

If workers have concerns that employers are not meeting their obligations under the Occupational Safety and Health Act of 1970 to provide safe and healthful workplaces, or are in violation of any specific OSHA standard, the worker or their representative may file a complaint with the OSHA Area Office that has jurisdiction for their location. Where OSHA finds that a manufacturer, importer, distributor, or downstream employer has violated standards, citations may be issued.

I appreciate receiving your letter. Please be assured that your concerns are important to us. If we may be of further assistance, you may contact Ms. Nancy Hauter, our Director of Health Enforcement, at (202) 693-2190.

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